This paper aims to improve the recovery characteristics of the receiving grid during DC blocking failures through DC emergency power support, revealing the mechanism of improving the power angle stability of the receiving grid through timely DC power increase and decrease. Based on the transmission pattern of “north-to-south power transmission” in a certain provincial power grid, the actual maximum long-term overload capacity of multiple DC lines is calculated, considering multiple constraints such as the strength of the receiving grid, the stability limit of AC evacuation channels, and DC overload capacity. A multi-DC emergency power support strategy after DC blocking is developed, avoiding the risk of AC transmission channel overload caused by power flow transfer, reducing the impact of large-capacity DC blocking and inappropriate DC power increases on the receiving grid, and achieving coordination between AC and DC systems. The effectiveness of the proposed strategy is verified through simulation.